This chapter deals with Immanuel Kant's treatment of each of the logical arguments by which Rational Theology has endeavoured to establish its case, and shows how ultimately they all have to fall back on to the Ontological argument, which in turn is inadequate to the burden. Kant refuted Rational Psychology by showing it to be based on paralogisms and Rational Cosmology by proving its assertions to be antinomies, so he refutes Rational Theology by establishing the necessary impossibility of all its proofs. All Rational Theology, or logical demonstration of the existence of God, lies in establishing the combination of two conceptions—the conception of an ens realissimum and the conception of necessary being. The Idea of God, like the Ideas of the Soul and the Universe, is perfectly valid as Idea, or as a problem Reason necessarily presents to itself for solution.